Over the past years, many experimental and clinical publications dealt with frontal fibrosing alopecia (FFA) and added new pieces of information to our understanding of this increasingly observed entity with its marked clinical phenotype. This review article provides comprehensive insights into common as well as distinctive features of lichen planopilaris and FFA as phenotypically distinct branches of what they refer to as the “same pathobiology tree”. Epithelial stem cell destruction, the critical roles for interferon-gamma and peroxisome proliferator-activated receptor (PPAR)-gamma-mediated signaling in immune privilege collapse and epithelial–mesenchymal transition as well as current hypotheses of how endocrine factors, environmental factors and oxidative stress may contribute to the disease process are summarized in a clear and descriptive way which also encourages further thinking about possible new treatment strategies.

While much research in the field of hair diseases naturally addresses questions related to pathophysiology and therapy, this retrospective case control study compared medical records of patients over the age of 18 diagnosed with AA (n=563) to the same number of matched control patients and came to the conclusion, that AA patients developed different types of skin tumors less frequently than the control group. The study is largely observational. It remains unclear, whether the observed numbers result from altered immune system and or increased awareness of enhance d UV exposure and better compliance with sun protection strategies. By addressing this question, however, the authors touch aspects of the disease relevant for patient information and consultation, which are practically relevant but usually do not receive much attention on the scientific level.

DPCP treatment of extensive AA is a very helpful therapeutic option for patients with AA totals or universalis not responding to immunosuppressive therapy, but the procedure is time-consuming because it requires repetitive presentations in specialized centers over weeks and months. Using tape stripping the Lee et al. monitored Interferon (IFN)-gamma, interleukin (IL)-2, IL-12 and IL-10 levels over time (week 1, month 2, month 4). Minor to moderate changes were observed, especially IFN gamma levels at later time points may reflect the course of treatment response. Yet, the baseline levels among the groups are quite different, and no statistically differences were observed at early time points which at this point could get give better guidance for patients. It is debatable as to whether superficial stratum corneum cytokines are the best source for prediction, but the non-invasiveness of the approach encourages further exploration of such biomarker assessments which could help give patients better guidance.

Immunohistochemical comparison of Folliculitis decalvans (FD) scalp skin biopsies from 15 patients allowed for differentiation in stable compared to active disease. Moreover, significant differences in the expression of the inflammasome –associated markers NALP1, NALP3, IL-1β, and of IL-8, which among others is induced in response to IL-1β and associated with neutrophil infiltration, were observed. These data present a novelty, because they support the exploration of IL-1β blockade in FD patients and could open up new perspectives for patients with very progressive forms of the disease which cannot be sufficiently controlled by conventional means.

Despite the wide range of mediators involved in hair growth and disease, the panel of available therapeutics is still limited. Translation into clinical applications is especially facilitated when compounds are already in use for other indications. Thus, exploratory work as conducted by Choi et al., is essential to open perspectives for novel drug classes in hair therapy. They investigated the effects of the phosphodiesterase 3 (PDE3) inhibitor Cilostazol, a compound with vasodilatory activity, in vitro on dermal papilla cells, ex vivo in whole organ cultures and in vivo upon topical application on C57BL/6 mice in comparison to topical minoxidil. Hair growth stimulation, enhanced dermal papilla cells proliferation, anagen induction associated with increased vessel formation were observed in accordance with its postulated mode of action suggesting that the compound could be an interesting new candidate molecule as hair growth therapeutic.

Epithelial-mesenchymal communication is a prerequisite for hair growth. Multiple signaling pathways and paracrine mediators involved in this finely tuned process have been reported in the past, but how such communication occurs is only partly understood. Herein, the authors identify exosomes secreted by dermal papilla cells (DPC-Exos) as one mechanism of such intercellular interactions. Injection of DPC-Exos in murine skin resulted in anagen induction and catagen delay, longer hairs hafts and larger bulges. Proliferation and migration of outer root sheath cells was enhanced involving b-catenin and Sonic hedgehog signaling. The data provide new insight in the role of these endogenously produced nanospheres in hair growth regulation but may also have impact on the development of effective drug delivery systems.